Protected carbon steel pipe for conveying flue gases in a heat exchange apparatus

ABSTRACT

A protected carbon steel pipe for conveying flue gases in a heat exchange apparatus, comprising an outer jacket made of carbon steel, which is provided internally with a plurality of contiguous sectors made of corrosion-resistant material and provided with variously shaped fins, a continuous layer made of corrosion-resistant material which is interposed and in contact between the outer jacket and the plurality of contiguous sectors being provided.

BACKGROUND OF THE INVENTION

It is known that there are heat exchange apparatuses, such as for example fire tube boilers for generating hot water or another heat transfer fluid, or different apparatuses of industrial thermal cycles, such as for example condensers, economizers, heat exchangers, which provide for the presence of pipes designed to convey flue gases produced by combustion in appropriately provided furnaces, inserted within a vessel which contains the fluid to be heated.

The pipes comprised within such apparatuses are made of carbon steel in order to ensure optimum quality of the welded joints between the pipes and the structures of the apparatuses, which are also made of carbon steel, and in the case of apparatuses such as for example condensing boilers, in which the water vapor contained in the flue gases condenses inside the flue gas conveyance pipes, forming corrosive condensation, the internal surface of the pipes is protected in different manners.

For example, pipes have been proposed which comprise an outer jacket which is made of carbon steel and is provided internally with a plurality of contiguous sectors which are made of corrosion-resistant material and are provided with variously shaped fins, but in this embodiment flue gases can penetrate between one sector and the other, with the consequent possibility of contact of such flue gas, which has cooled and therefore carries corrosive condensation, with the outer jacket, which accordingly is not protected fully.

SUMMARY OF THE INVENTION

The aim of the present invention is to provide a protected carbon steel pipe which comprises the elements described above and in which full protection of the outer jacket made of carbon steel is ensured.

The proposed aim is achieved by a protected carbon steel pipe for conveying flue gases in a heat exchange apparatus, according to the invention, comprising an outer jacket made of carbon steel, which is provided internally with a plurality of contiguous sectors made of corrosion-resistant material and provided with variously shaped fins, characterized by the presence of a continuous layer made of corrosion-resistant material which is interposed and in contact between said outer jacket and said plurality of contiguous sectors.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will become better apparent from the description of two preferred but not exclusive embodiments of the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein:

FIG. 1 is a transverse sectional view of the protected carbon steel pipe according to the invention;

FIG. 2 is a transverse sectional view according to a different embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 1, the reference numeral 1 generally designates a pipe according to the invention, which comprises an outer jacket 2 made of carbon steel and provided internally with contiguous sectors 3, 4, 5 made of corrosion-resistant material, such as for example aluminum alloy or stainless steel, and which are provided with fins 3 a, 4 a, 5 a respectively for the sectors 3, 4, 5.

An important feature of the invention is the presence of a continuous layer 6 made of corrosion-resistant material, which is interposed between the outer jacket 2 and the sectors 3, 4, 5 and adheres both to the jacket and to the sectors.

In this manner, the outer jacket 2 made of carbon steel has a complete protection against corrosion, because any infiltrations of flue gases between one sector and the other are blocked by the layer 6 and any contact between the flue gases and the jacket is thus prevented.

The embodiment of FIG. 2 illustrates a pipe 7 in which the outer jacket 8 made of carbon steel is provided internally with a plurality of sectors 9 which are made of corrosion-resistant material and are provided with fins 9 a, 9 b, which are shaped so as to define a plurality of flue gas conveyance modules which are substantially shaped like sectors.

In the second embodiment, the reference numeral 10 designates the continuous layer made of corrosion-resistant material which, interposed so as to adhere between the outer jacket 8 and the plurality of sectors 9, provides full protection of the jacket against any infiltrations of flue gases which may occur between one sector and another.

The described invention is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; all the details may further be replaced with other technically equivalent elements.

The disclosures in Italian Patent Application No. MN2006A000071 from which this application claims priority are incorporated herein by reference. 

What is claimed is:
 1. A protected carbon steel pipe for conveying flue gases in a heat exchange apparatus, comprising an outer jacket made of carbon steel, which is provided internally with a plurality of contiguous sectors made of corrosion-resistant material and provided with variously shaped fins, wherein a continuous layer made of corrosion-resistant material which is interposed and in contact between the outer jacket and said plurality of contiguous sectors is provided. 